Molded case circuit breakers, when an abnormal current such as an over current and a short-circuit current is applied to a circuit, protect the circuit by breaking the circuit. In molded case circuit breakers described above, it is necessary to interrupt an arc induced at an opening time that a fixed contact point and a movable contact point are separated from each other when breaking the circuit.
FIG. 1 illustrates a general molded case circuit breaker disclosed in Korean Patent Publication No. 2001-0043240.
Referring to FIG. 1, in general, a front compartment 12 and a rear compartment mutually divided from each other are located in a molded case circuit breaker 10. Also, a fixed contact point 60 and a movable contact point 61 are located in the front compartment 12 and a driving device for transferring the movable contact point 61, and particularly, an electrode shaft 78 is located in the rear compartment 14. In the general molded case circuit breaker 10 configured as described above, the electrode shaft 78 prevents transfer of an arc from the front compartment 12, to which the arc is actually induced, to the rear compartment 14. Also, the induced arc is transferred to an arc extinguishing chamber 58 located in front thereof.
However, the general molded case circuit breaker has limitations as follows.
Generally, the electrode shaft 78 is located inside the rear compartment 14. However, the rear compartment 14 has to additionally have a certain space, that is, a height to allow the driving device to operate. Accordingly, a height of the molded case circuit breaker 10 substantially increases.
Also, in general, as described above, the height of the molded case circuit breaker 10 substantially increases. Accordingly, while the fixed contact point 60 is being separated from the movable contact point 61, a floating arc is transferred to a rear end of the front compartment 12 and the rear compartment 14, thereby causing damage in the driving device.